Haldan (Keffer) Hartline

Physiologist, born in Bloomsburg, Pennsylvania, USA. He studied at Johns Hopkins University, then taught at Cornell (1931–49) and Johns Hopkins (1949–53), and became professor of physiology at the Rockefeller University, New York City (1954–74). By the use of very small electrodes applied to cells in the eyes of frogs and crabs, he was able to show how an eye distinguishes shapes. He shared the 1967 Nobel Prize for Physiology or Medicine for work on the neurophysiology of vision.

Hartline began his study of retinal electrophysiology as a National Research Council Fellow at Johns Hopkins University, Baltimore, receiving his M.D. After attending the universities of Leipzig and Munich as an Eldridge Johnson traveling research scholar, he became professor of biophysics and chairman of the department at Johns Hopkins in 1949. One of Hartline's graduate students at Johns Hopkins, Paul Greengard, later also won the Nobel Prize. Hartline joined the staff of Rockefeller University, New York City, in 1953 as professor of neurophysiology.

Hartline investigated the electrical responses of the retinas of certain arthropods, vertebrates, and mollusks because their visual systems are much simpler than those of humans and are thus easier to study. Using minute electrodes in his experiments, he obtained the first record of the electrical impulses sent by a single optic nerve fibre when the receptors connected to it are stimulated by light. Hartline thus built up a detailed understanding of the workings of individual photoreceptors and nerve fibres in the retina, and he showed how simple retinal mechanisms constitute vital steps in the integration of visual information.